Re: [Gnucap-devel] System simulation

[al davis]

On Sunday 18 March 2007 06:07, Thomas Lundin wrote:
> I played around with gnucap a few years ago and thought that
> the interactivity would make it "easy" to get it to talk to
> an micro-controller simulator. And now when micro-controller
> simulator people has joined up with the circuit simulator
> people on this list I thought I'd get some opinions.
>
> What got me into this is that it's possible to continue a
> transient analasys where it left off after it has been
> stopped. If I recall correctly it is possible to change
> component values around while it's halted and continue with
> those new values.

That still works :-)

> My thought was to create a new logic device that works as an
> "digital generator" that can be changed between 1 and 0 from
> the command line. The plan was then that the MCU-simulator
> would interact with gnucap through a pipe.

The existing logic device is scheduled for some big changes.  
Probably the best way to accomplish what you want is a "bm" 
function.  Any component can have an expression, with a 
function, like PWL, TANH, and the Spice time dependent sources.  
These are defined in the "bm" files.  (Behavioral modeling, 
1980's style).  

What I recommend is to make a new bm file, maybe you could call 
it "bm_external.cc" that lets you set a value from a pipe.  
Another approach might be to define a new device with 
a ".model" file.

> Would this be enough from a gnucap point of view to get
> gnucap and a MCU-simulator (gpsim for instance) be able to
> act as system simulator where you can simulate your software
> together with your electronics?
>
> A second and required step would be to add ADC's and DAC's.

The plan is full Verilog-AMS, eventually.  Before that, you 
could make those as ".model" files.  The ".model" files are 
compiled into ".cc" files by "gnucap-modelgen".  Compiling 
that ".cc" makes a ".so" that can be used as a plugin.  This 
functionality exists now, in the development snapshot.

Future plans include being able to "attach foo.cc" 
or "attach "bar.model" with a single command, and have the 
compiling done automatically.